Blast-furnace construction



Dec. 25, 1923.

v E. B. KIRBY BLAST FURNACE CONSTRUCTION Jfifi Flled eb. 16, 1920 names Deezfi, res. I I

units are Wannnm'on'n emu, or roan, n. Y.

roan-ace consrnncrron.

Application nee February 16,1920. serial na'saae'zo.

- tion Serial No. 358,969, filed Febflti, 1.920,

may be carried out.

A. further object of the invention is to provide a furnace having certain characteristic features which may be useful inconnection with blast furnace construction for purposes other than that of carrying out the particular method to which reference has before been made.

Additional objects of the invention will appear more at large as the description pro coeds. 7

Reference should be had to the accompanying drawings forming a part of this specification, in which Fig. 1 is a sectional elevation of a furnace embodying my invention; Fig. 2 is a sectional elevation at right angles to the elevation of Fig. 1; Fig. 3 is a sectional elevation showing a portion of a furnace embodying a modified construction; Fig. 4 is a sectional plan view of'a furnace embodying the invention; Fig. 5 is an elevation with portions in section embodying a feature of construction of the furnace. Figs. 6 and 7 show two other forms of lower tuyeres and Fig. 8 shows the nozzles of a tuvere and a fuel injector.

The method of operating a blast furnace or similar furnace as set forth in my copending application embraces in general the method of feeding into the furnace the material to be treated and the solid fuel such as coke or anthracite so that they will descen through the furnace as separate contactin columns. The material column is indicated at 4L5 Fig. 2 and the fuelcolumn at 46. These columns contact with each other along a curved surface of equilibrium whose shape and position depend 'on the relative specific gravities of the material and the fuel and upon other factors;- the surface being at approximately the central zone of the furnace. The particles of the column of .fuelare made of smaller average size.

than the particles of the material columnf whereby the average interstices of the latter are larger and gases will ascend through the column of material rather than the fuel column. An oxidizin blast is introduced at substantially the sur ace of contact between the columns of material. and fuel, adjacent the lower end of these columns, and the gases which are formed'ascend substantially entirely through the column of material.

The process preferably proceeds in a manner to provide only a suficient amount of combustion at the lowerportion of the-furmice to insure the formation of carbon monoxide. There is subsequently. intro:

duced into the columns of material at a- I hlgher elevation a supplementary oxidizing blast so that the carbon monoxide is burned to carbon dioxide, thus liberating the remainingheat incident to the combustion of the fuel.

introduces the main blast isso located asto deliver the blast upon the fuel adjacent the plane of contact between the descending columns of charged material and solid fuel. The supplementary blast, however, is delivered into the column of material so that it will not reach the fuel.

In form the furnace is preferably rectangular, although the shape may be varied. somewhat from this form so long as its sha permits the material andthe fuel to be introduced in a manner to form'the two contacting descending columns.

The material and the fuel are introduced at a proper hei ht by any of the well-known arrangements or charging, one of these being indicated at 5 in the drawings and the upper part of the furnace is provided with an of the well-known means for carrying o the gases formed, but these are not illustrated inasmuch as they, like charging arrangements, are all well known in the art. J

The main blast of the furnace maybe introduoed in any way which will enable it. to act upon the fuel at or near its contact with the column of material. In one mode of construction the main blast tuyeres of which one is indicated at 8 Fig. 2 and Fig. 8 are located along the fuel side wall of the furnace near its base and extend into the fuel column nearly to the contact. They are preferably adjustable in any well-known way for instance, the water-cooled tuyere 8 may be mounted in a sleeve 10 wh ch has a ball and socket connection or fitting into the wall of the furnace, so that it may be moved slightly in an angular direction and also the tu ere 8 may be moved inwardly or outwardfy in the sleeve 10. The tuyere 8 is connected by means of a ipe with a blast main 11. The nozzle of t e tuyere opens downwardly to such an extent as to prevent the fuel from flowing into it; The velocity of the gas flow away from the nozzle and the non-conducting qualities of crushed fuel protect the nozzle. As before stated, there are a series of such tuyeres which extend through the openings 9 in the wall of the furnace as indicated in Fig. 1.

In an alternative method of construction a single continuous tuyere is constituted by an inverted water-cooled trough 47 Fig. 6 extending between the end walls through the fuel column, near and parallel to its contact with the material column. This trough constitutes a conduit which is connected to the blast main outside the furnace. Its continuous open bottom presents a large area for the blast to enter the interstices of the fuel while the fuel cannot flow up into the conduit.

A similar trough conduit serving as a tuyere may be constructed in the furnace wall alongside of the fuel column 49 Fig. 7. In this case the fuel column is narrowed as much as practicable as illustrated in the drawing, which shows the narrowing accomplished by a projection of the wall which permits the column to widen again below the tuyere.

Extending through the side wall of the furnace which is against the column of material and at an elevation above the zone of reduction are a series of auxiliary tuyeres" such as indicated at 29 Fig. 2 for the ur- Jose of introducing the supplementary 1) ast. Zach tuyere is connected with a blast'main 30. There may be more than one suchrow of auxiliary tuyeres and such an additional row is indicated at 31. I

As a part of the method for operating a blast furnace as set forth in my application as before mentioned, the main blast introduced near the base of the furnace is permitted to form carbon monoxide such as may result from the temperature employed and this carbon monoxide is allowed to act upon the material as it descends through the zone of reduction above the main tuyercs.

The formation of carbon monoxide liberates only one-third of the amount of heat which would be evolved from the complete burning of the fuel. The carbon monoxide ascends through the interstices of the material column and after passing throughthe zone of reduction within which the carbon monoxide performs its necessary reactions withthe material, and meeting with the auxiliary blast introduced through the row of tuyeres 29 and additional rows of tuyeres if they be used, the carbon monoxide is completely burned to form carbon dioxide thus liberatin the remaining two-thirds of the heatiincitfent to the combustion of the originalffnelf he auxiliary tuyeres are introduced through the furnace walls so that the blast therefrom will enter the column of the charged material and not reach the column of fuel and as clearly explained in connection with the method set forth in my prior application, it .is essential that the hot carbon dioxide ases ascend through the column of material and not through the column of fuel for if they did ascend through the latter the carbon dioxide would be reconverted to carbonmonoxide by contact with the hot fuel.

Up to thepresent time the diflieulties attending the use of injectable fuels in blast furnaces have either prevented or limited their applications and in most cases have overbalanccd the advantages of such fuels. Since these difficulties are mainly due to pasty conditions affecting penetration, and to the chilling effect of injection upon the solid fuel, especially when oil or powdered coal is used, the open interstices and the diminution of nitrogen secured by my process, makes it now possible to evade such difficulties and to utilize all such fuels freely.

It may be explained that the injectable fuels to which I refer constitute a well-understood and clearly defined class distinguished by having the peculiar qualities necessary for combustion within the interstices of a blast furnace column.

Such fuel to be injectable must either be gaseous or be liquid or be a solid powdered finely. They must thus be capable of being scattered by the injection force into liquid globules or solid particles, which are small enough to be carried by the injection current through the fine interstices of a blast furnace column and to mix with the blast and to be consumed quickly by virtue of their small size, before choking these interstices.

F or convenience, therefore, I shall refer to all such fuels as injectable fuel.

In those cases where it is desired that the heat for smelting shall be supplied wholly or partly by fluid or pulverulent fuel instead of solid fuel the injection of this is made close to the lower blast which is to burn it. There are well-known and standlid aeraeee ard forms of injectors for each kind of these injectable fuels and l have therefore merely indicatedby the pipe 12' and 13 Figs. 2 and 8 that when such fuel is required some suitable injector is preferably placed within the tuyere or delivering into it, thus afi'ecting a de ivery of this fuel with the blast.

In the inverted trough form of tuyere the fuel injection apparatus is placed along the upper part of the conduit thus formed asat 48 Fig. 6, and 50 Fi 7. This apparatus distributes the injecta le fuel with the blast into the interstices of the solid fuel along the open bottom.

When all the smelting heat is supplied by injectable fuel the column of solid fuel is not consumed but serves through its open interstices and plane of contact, to transmit the gases of combustion past the zone where the material, nearing its fusion point, hecomes pasty and impermeable.

In those cases where injectable fuel is used therefore, it is desirable to provide means for flowing 0d the solid fuel column so that it may have a regular descending movement which will maintain the surface of contact in the desired position. Moreover, even in the usual recess of smelting with solid fuel only, it is desirable to have such means for regulating the descent of the fuel column.

This is accomplished by means of a seriesof inclined discharge pipes or conduits such as indicated at 25. These conduits extend through the wall of the furnace on the fuel column side and are preferably watercooled. The passage of the fuel through the conduit is controlled by suitable valves 26 which are illustrated as a part of each con duit. These are simply ate valves which may be opened to any desired degree to permit the passage of fuel. The conduits connect with a suitable conveyor mechanism which may be of any type desired such as a screw conveyor located within the housing 27. The fuel which is thus drawn away is utilized by being re-charged in the upper part of the furnace.

For purposes of furnace manipulation a series of ordinar tap holes 18 is indicated along the wall 0 the furnace at the hearth bottom.

To provide for the increased rapidity of fusion occurring in my process and the decreased storage space for molten products, it has been important to rovide means for the continuous removal of the molten products in place of the customary intermittent tapping.

Inverted siphon continuous flow taps have avery limited application at the present time because of the difficulties in starting and in keeping the tap channel hot or in opening a channel when it cools. The present invention, therefore, provides a means for maintaining the heat of the channel when the heat of the current becomes insufficient and also for heating the channel when the flow in it becomes frozen. v This means'consists of arrangements for electric resistance heating of the channel and this resistance heating makes it possible to utilize the inverted siphon continuous flow tap for any moltenproduct. v

n smelting some materials, the bottom of the blast furnace hearth also chills occasionally, so as to obstruct the flow of prodnets to the taps and for such work the same arrangements for electric resistance heating are provided or extended so as to maintain a free channel along the hearth bottom to the tap or taps.

The resistance heating of either a tap channel or a hearth channel requires the passing of an electric current along a suitable resistor which extends alongside or beneath the channel or which occupies it wholly or partly.

The material of the resistor must be adapted to the particular products which are being made in each furnace and is therefore not restricted to any specific material. For instance, carbon or graphite may be used as the resistor material for heating the hearth or tap channels except in cases where the molten product dissolves carbon or reacts with it. In such cases suitable resistor material other than carbon or graphite should be used,

Moreover, I do not restrict myself to any particular current or means of causing it to traverse the resistor and have indicated two methods in the same drawing for purposes of illustration. In one of these the tap channel 17 Figs. 1 and t is partly constructed in an elongated mass of carbon which thus constitutes the sides and bottom of the channel. By means of water-cooled electrodes at 20-and 22, a suitable current is passed along this carbon resistor.

The channel of flow 7 constructed in the sloping hearth bottom for convenience in receivin and leading the stream of molten pro nets to one or both taps, in this case conceived as draining to the left-hand tap, also has its sides and bottom composed of carbon. By means of the electrodes 22-23 a current may be sent through this carbon resistor or by the electrodes 20-23, the same current may heat both the tap channel and the hearth channel. By extending this construction to the right-hand tap, the same current will heat both tap channels. and the hearth channel. In Fig. 3 a carbon resistor 35 is shown laid along the bottom of the tap channel and supplied gv 'zith current through the electrodes 36 and The other method illustrated and which is preferred for most cases is shown as an plied to the right-hand tap only. Here a miniature electric induction furnace of any of the well-known types is employed to create the current through the resistor. The illustration also shows the utilization of a furnace product for the resistor such as the metal from an iron blast furnace.

The resistor 40 Figs. 1-4-5 associated with the tap channel, has its ends connected by a conductor 39-39 so asto make the resistor part of a rectangular conducting ring which constitutes the closed secondary circuit of an electric induction furnace transformer. I

This closed ring of the secondary circuit, which ring may be of any convenient form, links through a closed core ring of iron which constitutes the magnetic circuit of the transformer. This iron ring may also be of any convenient form and is shown as an upright rectangular ring 41 placed outside of the furnace walls.

The primary circuit is a conductor Wound for the required number of turns around any convenient part or parts of the iron core ring. It is indicated-by one or both of the coil spools 42 which are placed outside of the furnace walls in positions protected from the tap hole heat. The various designs of induction furnaces are well-known and I do not limit myself'to any one type or construction.

An alternating current supplied to the primary circuit coils induces a secondary alternating current of lower voltage within the rectangular closed secondary circuit 39-40 by which that portion of it constituted by the resistor 40 alongside of or Within the tap channel, is brought to the necessary temperature thus heating the channel and its contents.

The portion 40 of the secondary circuit associated with the channel to be heated, may be of any suitable resistor material, fusible or infusible, while the rest of the circuit 39 may be of any conducting material, fusible or infusible, since it is not necessary to generate heat in this part of the circuit.

Where the blast furnace is used for the production of iron, the metal product itself may conveniently constitute the entire secondary circuit as represented by 40-39. That is to say, this circuit may be formed by a rectangular ring pool of iron which is molten when the furnace is in operation and yet when the furnace is shut down and subsequently started, the resistance of the solidified iron is sufficiently great to create the desired heat.

In this case the continuous flow of iron passes along that part 40 of the rectangular pool, which occupies the tap channel and overflows the dam 51 which retains the pool. This pool is shown with a greater conducting cross-section in those parts 39 of the savages ring where conduction rather than heat generation is desired. If the tap is used for iron only the overflow damis placed at such a height that the pool level will close the tap channel and trap the blast.

f it is desired to also pass the slag through the same tap the dam is placed low enough for the pool surface to stand below the top of the channel and leave a passage way for the slag stream. This stream is kept from the iron overflow dam by the inverted dam 52 and passes over the slag overflow dam 16.

may also be utilized to handle a product like calcium carbide which has little conductivity when cold and which dissolves carbon. Here the light carbide, like the ironslag, will flow through the tap over a molten pool of the heavy iron or such alloy of iron as is formed during operations and this pool is heated when required by passing an electric current through it. A small by-product of carbide smelting is usually some iron containing much silicon.

In first starting the furnace, ordinary lron would be inserted but this would gradually have its silicon contents raised to that of the furnace product passing through the pool. I therefore use the term iron hereafter without limiting myself as to its degree of purity for the reason that the composition of the metal is not material so long as it is heavier than the other product, is immiscible with it, does not evaporate too fast at the temperature used and possesses electric conductivity enough when cold to heat up. v

If a furnace produces no metal to displace the original filling, the latter will remain as a permanent resistor for heating the slag or other light product flowing over it. It is obvious that a variety of metals and alloys have the aforesaid qualities to such an extent that they may be thus utilized as permanent pool resistors for suitable light products flowing over them and I do not restrict myself to any one.

It will be understood that after the furnace has been started and while in its normal operation the continuous flow of molten products through the tap openings will of itself maintain the channels in open condition so that. the electric heating is not needed during such normal operation but is only required in an emergency or to be employed for a short time at starting or during occa' sional interruptions or iregularities which are inevitable in blast furnace operations.

It therefore follows that the cost of this electric heating will be but a small item.

Having described my invention, I claim:

1. A blast furnace having an interior space adapted to permit the maintenance of separate descending contacting columns of garages l material to be treated and solid fuel, and a tuyercso placed as to discharge upon the fuel substantially at its surface ofcontact with the material column; 2. K blast furnace having an interior space ada ted to permit the maintenance of separate escending contacting columns of material to be treated and solid fuel, and a separate descending,contacting columns of material to be treated and solid, fuel, a

tuyeieso placed as. to discharge upon the fuel substantially at its surface of contact wi'thlthe material column, and an auxiliary tuyere at 'an elevation above the zoneof reduction andso placed that its blast will onter the material without impinging upon the fuel column.-

4. A blast furnace having an interior space adapted to permit the maintenance of separate descending contacting columns of material to be treated and solid fuel, a tuyerc so placed as to discharge into the fuel near its surface of contact with the material column, andan auxiliary tuyere at an elevation above the zone of reduction and so placed that its blast will enter the material without impinging upon the fuel column.

5. A blast furnace having an interior space adapted to permit the maintenance of separate descending contacting columns of material to be treated and solid fuel, a tuyere so placed as to discharge upon the fuel substantially at its surface of contact with the material column, and means of injccting injectable fuel with the blast.

6. A blast furnace having an interior space adapted to permit the maintenance of separate descending contacting columns of material to be treated and solid fuel, a

tuyere so placed as to discharge into the fuel near its surface of contact with thematerial column, and means'of'injecting injectable fuel with the blast.

7. A blast furnace having an interior space adapted to permit the maintenance of separate descending contacting columns of material to be treated and solid fuel, a tuyerc so placed as to discharge upon the fuel substantially at its surface of contact with the material column, an auxiliary tuyere at an elevation above the zone of reduction and so placed that'its blastwill enter the material without impinging upon the fuel column, and means of injecting inject able fuel with the main blast.

8. A blast furnace having an interior space ada ted'topermit the maintenance of separate escending contacting columns of material to be treated and solid fuel, a tuyere so placwi as to discharge into the fuelnear its surface of contact with the material column, an auxiliary tuyere at an elevation above the zone of reduction and so placedthat its blast will enter the material without impinging upon the fuel column,

and means of injecting injectable fuel with the main blast.

9. A blast furnace having an interior space adapted to permit the maintenance of separate descending contacting columns'of material to be treated and solid fuel, a tuyere consisting of an inverted watercooled trou h extending horizontally through the fuel col umn near and parallel to its contact with the material column.

10. A blast furnace having an interior separate descending contacting columns of furnace having its discharge opening practically continuous alongside the fuel column parallel to its contact with the material column, said opening being directed sufliciently downward to prevent the inflow of fuel.

11. A blast furnace having an interior space adapted to permit the'ma-intenance' of space adapted to permit the maintenance -of naterial to be treated and solid fuel, 'a tuyere consisting of a blast conduit extend ing horizontally along the fuel wall of the separate descending contacting columns of 3 material to be treated and solid fuel, a'-'- tuyere so placed as to discharge into the fuel near its surface of contact with the material column and having a discharge opening directed sufliciently downward to prevent theinflow of fuel, and means Within said tuyere for injecting in'ectable fuel with the blast.

12. A blast urnace having an interior space adapted to permit'the maintenance of separate descending contacting columns of material to be treated and solid fuel, a tuyere for introducing the blast, a sufiicient opening below the tuyere for the solid fuel to flow out of the furnace, and a fuel conduit of suficient length to prevent escape of blast and means for regulating said flow.

13. A blast furnace having an interior space adapted to permit the maintenance of separate descending contacting columns of material to be treated and solid fuel, a tuyere for introducing the blast, means of injecting injectable fuel with the blast, a

suficient opening'below the tuyere for thellt) fit

above the temperature of said molten product and being heavier than and'immiscible with it, one terminal of an electric circuit being in contact with the outside end of said metal pool and the other terminal with the end inside of the furnace and means for passin a. current through said circuit.

15. metallurgical furnace having a tap charged and this pool constituting the secondary circuit of an electric induction furnace transformer.

16. A n'ictallurgical furnace having a tap, a resistor associated with the channel of said tap composed of one of the products from the furnace operation, an overflow dam retaining said resistor in-a pool of such shape as to constitute a closed circuit which is the secondary circuit of an electric induction furnace transformer, the surface of said pool being sufficiently below the top of said channel to leave passageway for a sec ond molten product, and an inverted dam so placed as to pass the lower product and divert theupper product. I

17. A metallurgical furnace having an inverted siphon continuous tap, a resistor associated with the channel of said tap composed of one of the products from the furnace operation, an overflow dam retaining said resistor in a pool of such shape as to constitute a closed circuit which is the secondary circuit of an electric induction furnace transformer, the surface of said pool being sufficiently below the top of said channel to leave passageway for a second molten product, and an inverted dam so placed as to pass the lower product and divert the upper product.

18. A blast furnace having an inverted siphon continuous tap, an infusilole, insoluble resistor reaching from the inside to the outside of the furnace, and so placed along the channel of said tap as to be in continuous contact with the stream passing through it, terminals of an electric circuit connected to the inside and outside. ends of said resistor and means for passing an electric current through it.

- 19. A blast furnace having an inverted siphon continuous tap, the channel of which has a cross section small compared to its length, an overflow dam so placed as to keep the channel filled with a permanent pool of the product being discharged, an electric conductor having one terminal in contact with the outside end of the pool and the other with. the end inside of the furnace and forming with said pool a closed circuit which constitutes the secondary circuit of an electric induction furnace transformer.

20. A blast furnace having in its hearth bottom a contracted channel of flow connecting with the channel of an inverted siphon continuous tap, the cross section in each channel being small in comparison with its length, an overflow dam so placed as to create a permanent pool of the molten product occupying the continuous channel thus formed by the two channels aforesaid, an electric circuit having its terminals in contact with the opposite ends of this pool and means for passing a current through the circuit.

21. A blast furnace comprising a chamber with means at the top for introducing the material to be treated and its solid fuel, said chamber havin a horizontal cross-section which is approximately rectangular and of such proportions as to permit the maintenance of separate columns of material and fuel, and a blast tuyerc near the base of the chamber consisting of an inverted water-cooled trough so placed as to extend horizontally through the fuel column parallel to its contact with the material column and connected with the blast.

22. A blast furnace comprisng a chamber with means at the top for introducing the material to be treated and its solid fuel, said chamber having a horizontal cross-section which is approximately rectangular and of such proportions as to permit the maintenance of separate columns of material and fuel, a blast tuyere near the base of the chamber consisting of an inverted watercooled trough so placed as to extend horizontally through the fuel column parallel to its contact with the material column and connected with the blast and means for injecting injectable fuel placed within said inverted trough.

In testimony whereof, I hereunto aflix my signature.

EDMUND B. KIRBY. 

